A variety of systems and devices have been made and used for treating morbid obesity. Some such systems and devices include adjustable gastric band systems, which are operable to restrict the flow of food from the esophagus into the stomach. Some gastric bands include a fluid-filled elastomeric bladder with fixed endpoints that encircles the stomach just inferior to the gastro-esophageal junction. When fluid is added to the bladder, the band expands against the stomach, creating a food intake restriction or stoma in the stomach. To decrease this restriction, fluid is removed from the bladder. Examples of gastric bands are disclosed in U.S. Pat. No. 7,416,528, entitled “Latching Device for Gastric Band,” issued Aug. 26, 2008, the disclosure of which is incorporated by reference herein; and U.S. Pub. No. 2006/0211914, entitled “System and Method for Determining Implanted Device Positioning and Obtaining Pressure Data,” published Sep. 21, 2006, the disclosure of which is incorporated by reference herein. Fluid may be added to the bladder by using a syringe and needle (e.g., Huber needle) to inject the fluid through an implanted injection port that is coupled with the bladder. Similarly, fluid may be removed from the bladder by using a syringe and needle to withdraw the fluid through the implanted injection port.
In addition to or as an alternative to an injection port, a gastric band system may include a pump that is used to adjust the level of fluid in the bladder of the gastric band. An example of a gastric band system incorporating a pump is described in U.S. Pat. No. 7,390,294, entitled “Piezo Electrically Driven Bellows Infuser for Hydraulically Controlling an Adjustable Gastric Band,” issued Jun. 24, 2008, the disclosure of which is incorporated by reference herein. Other examples of such a system are described in U.S. Pat. No. 7,351,240, entitled “Thermodynamically Driven Reversible Infuser Pump for Use as a Remotely Controlled Gastric Band,” issued Apr. 1, 2008, the disclosure of which is incorporated by reference herein.
Other methods and devices to treat morbid obesity or other conditions include the use of gastric sleeves, gastric valves, space occupying devices, and bulking devices. Gastric sleeves may be placed within an interior portion of the stomach (or elsewhere within the gastrointestinal tract) instead of being placed about an exterior of the stomach. Some types of gastric sleeves may also be configured to restrict the absorption of nutrients within the gastrointestinal tract (e.g., within the duodenum). Examples of gastric sleeves are disclosed in U.S. Pat. No. 7,037,344, entitled “Apparatus and Methods for Treatment of Morbid Obesity,” issued May 2, 2006, the disclosure of which is incorporated by reference herein.
Gastric valves may be placed inside or outside the stomach (e.g., at the esophagus or pylorus, etc.) and may selectively restrict the flow of food into the stomach. Like a gastric band, the degree of restriction provided by a gastric valve may be based at least in part on an amount of fluid in one or more inflatable portions of the gastric valve. Such a fluid level may be adjusted in a variety of ways. Examples of gastric valves are disclosed in U.S. Pub. No. 2006/0235448, entitled “Artificial Gastric Valve,” published Oct. 19, 2006, the disclosure of which is incorporated by reference herein.
Space occupying devices may include a device such as a balloon that is implanted in the stomach. The space occupying balloon may be substantially non-digestable, and its presence in the stomach may lead to relatively early satiety. The amount of space occupied by the balloon may be based at least in part on an amount of fluid in the balloon. Such a fluid level may be adjusted in a variety of ways. In addition to occupying space within the stomach, a space occupying device may even form a restriction within the stomach by providing a relatively narrow passageway for passage of food, with the size of the passageway being based at least in part on an amount of fluid in the space occupying device. Examples of space occupying devices are disclosed in U.S. Pub. No. 2008/0103593, entitled “Use of Biosurgical Adhesive on Inflatable Device for Gastric Restriction,” published May 1, 2008, the disclosure of which is incorporated by reference herein.
Bulking devices may include a device that is placed between layers of the stomach to reduce the internal volume or capacity of the stomach. Like a space occupying device, presence of a bulking device in the stomach may lead to relatively early satiety, and the amount of volume reduced by the presence of the bulking device may be based at least in part on an amount of fluid in the bulking device. In addition or in the alternative, a bulking device may be placed between layers of the esophagus to restrict the flow of food into the stomach. Examples of an adhesive being used as a bulking device are disclosed in U.S. Pub. No. 2008/0154228, entitled “Use of Biosurgical Adhesive as Bulking Agent,” published Jun. 26, 2008, the disclosure of which is incorporated by reference herein, though it should be understood that such an adhesive may be replaced or supplemented with one or more inflatable members. Additional examples of bulking are disclosed in U.S. Pub. No. 2006/0247768, entitled “Bulking of Upper Esophageal Sphincter for Treatment of Obesity,” published Nov. 2, 2006, the disclosure of which is incorporated by reference herein.
It should also be understood that the above-described devices to treat morbid obesity or other conditions may lack a fluid filled member, such that the devices may be adjusted using some method other than adjusting the amount or pressure of fluid in the device. For instance, such devices may be adjusted on a mechanical or electromechanical, non-hydraulic basis.
Hydrogels have also been used in a variety of biomedical applications. For instance, examples of such uses are described in Peppas, Hydrogels in Medicine and Pharmacy, CRC Press, Boca Raton, Fla. (1986); and Hoffman, “Hydrogels for Biomedical Applications,” Adv, Drug Deliv. Revs., 54, 3-12 (2002). Hydrogels may be configured to respond to changing conditions in their environment, such as temperature, pH, electric fields, ionic strength, the presence of a liquid, chemical stimuli, etc. Examples of environmentally responsive hydrogels (and uses thereof) are described in Peppas, “Physiologically Responsive Gels,” J. Bioact. Compat. Polym., 6, 241-246 (1991); Qiu, et al., “Environment-Sensitive Hydrogels for Drug Delivery,” Adv. Drug Deliv. Revs., 53, 321-339 (2001); Byrne, et al., “Molecular Imprinting within Hydrogels,” Adv. Drug Deliv. Revs., 54, 149-161 (2002); Jeong, et al., “Thermosenstive Sol-Gel Reversible Hydrogels,” Adv. Drug Deliv. Revs., 54, 37-51 (2002); and Miyata, et al., “Biomolecule-Sensitive Hydrogels,” Adv. Drug Deliv. Revs., 54, 79-98 (2002).
Physiological changes of the digestive system between fasting and consumption may be described in terms of changes in gastric acidity as measured using pH (the log concentration of hydronium ion concentration, or log [H+]). The pH scale spans from 1 (acidic) to 14 (basic), with 7.0 being neutral. During the fasting state, the stomach pH may be relatively low (acidic). With meal ingestion, intragastric acidity may be buffered, with an elevation of gastric pH. The change in pH may occur rapidly with the initiation of consumption as food enters into the stomach. This change may also occur even in light of the secretion of gastric acids continuously during consumption. The buffering capacity of foods, including acidic or “spicy” foods, may be sufficient to provide a significant change in gastric pH.
Some examples described below relate to the use of a hydrogel to make adjustments in a method or device for treating morbid obesity in accordance with changes in environmental conditions within a patient. While a variety of devices and methods have been made and used to treat morbid obesity, it is believed that no one prior to the inventor(s) has made or used an invention as described herein.
The drawings are not intended to be limiting in any way, and it is contemplated that various embodiments of the invention may be carried out in a variety of other ways, including those not necessarily depicted in the drawings. The accompanying drawings incorporated in and forming a part of the specification illustrate several aspects of the present invention, and together with the description serve to explain the principles of the invention; it being understood, however, that this invention is not limited to the precise arrangements shown.